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Troubleshooting Brake Controller Installations

Even the most experienced installer will encounter it from time to time: the brake controller installation is finished, the wires have all been run, but something is going wrong. Whether your controller is showing an error message or the trailer brakes just aren't working, there are a number of troubleshooting techniques you can use to get the problem fixed and get back on the road. Using the following information and testing procedures, you should be able to pinpoint and eliminate the most common issues encountered during and after a brake controller installation.

Common Brake Control Issues

Problem

Possible Issues

Testing Procedures

Brake controller display does not show that trailer is connected.
  • Short on brake signal wire, trailer or vehicle side.
  • Corrosion in trailer and/or vehicle plug.
  • Short on brake magnets on trailer.
  • Malfunctioning brake magnet(s).
  • Method 1
  • Method 2
  • Method 3
  • Method 4
Brake controller loses connection to battery ground.
  • Ground wire was not connected to negative battery terminal, ground area does not have solid connection to ground.
  • Adapter wiring does not match OEM connector on vehicle.
  • Ground connection to negative battery terminal is loose.
  • Ground wire has been damaged and exposed wiring is touching a metal area.
  • Connect ground wire to negative battery terminal.
  • Method 1
  • Method 3
Brakes are applying too aggressively for the brake controller settings.
  • Brake assemblies are not properly adjusted.
  • Boost/Gain on brake controller is set too high for trailer size.
  • Adjust brakes properly (see video).
  • See brake control owner's manual for proper boost/gain settings for trailer size.
Trailer brakes only work with manual control, not with brake pedal. (Be sure to test for proper brake controller function with unloaded trailer in a safe area where you can reach low road speed before you determine that the brake controller is not working)
  • Incorrect stoplight wire connection.
  • Adapter wiring layout does not match OEM connector on vehicle.
  • Method 1
  • Method 2
Brake controller detects an overload condition during use.
  • Trailer has too many brakes for brake controller to handle.
  • Corrosion in trailer and/or vehicle plug.
  • Brake signal wire on trailer is damaged, exposed wiring is touching metal area or another circuit.
  • Malfunctioning brake magnet(s).
  • Check brake control owner's manual for limit on number of trailer brakes.
  • Method 1
  • Method 3
  • Method 4
Display is erratic while braking.
  • Short to battery on 12V wire connection.
  • Short on brake signal wire, trailer or vehicle side
  • Corrosion in trailer and/or vehicle plug.
  • 12V wire was not connected to vehicle battery, 12V source used is not constant.
  • Method 2
  • Method 3
  • Connect 12V wire to positive battery terminal.
Brake controller detects a short on the brake wire while vehicle is idling.
  • Corrosion in trailer and/or vehicle plug.
  • Brake signal wire on trailer or vehicle is damaged, exposed wiring is touching metal area.
  • Method 3
Trailer brakes engage when it is plugged into the vehicle.
  • Incorrect stoplight wire connection.
  • Corrosion in trailer and/or vehicle plug.
  • Adapter wiring does not match OEM connector on vehicle.
  • Method 1
  • Method 3
Brake controller does not turn on.
  • Connection to battery is not complete.
  • Vehicle is missing a fuse or relay required to power 12V power circuit.
  • Adapter wiring layout does not match OEM connector on vehicle.
  • Method 1
  • Check fuse block for missing fuse/relay. See vehicle-specific FAQ if available, or check owner's manual.

Basic Testing Procedures

Method 1: Verifying Correct Wire Connections (Hard Wire Installs)

  • Make sure that each wire is connected in the correct location. Standard wire colors are listed, but check connections by function if colors vary.
    Brake Controller Wire Colors Image
  • Verify that the white brake controller wire (ground function) is connected to the negative battery terminal.
  • Verify that the black brake controller wire (12V power function) is connected to the positive battery terminal with a 20 or 30 amp circuit breaker installed in line. For trailers with 2-4 brakes, use a 20 amp breaker and for trailers with 6-8 brakes, use a 30 amp breaker.
  • Use a 12V probe-style circuit tester to verify the stoplight wire (red) connection (Figure 1). Click here to see our circuit testers. The tester should show power when the brake pedal is pressed, and should not show power when the pedal is released.
  • If all connections are correct, proceed to Method 2.
Verifying Correct Wire Connections for Hard Wire Installs Image

Method 1: Verifying Correct Wire Connections (Plug-in Installs)

  • Use a 12V probe-style circuit tester to verify that power is present at OEM connector. You should be able to get a solid power reading on one pin/slot, a reading on a second pin/slot only when the brake pedal is pressed, and at least two other pins with no power present.
  • Verify that the pin/slot layout of the wiring adapter you are using matches the layout in the OEM connector. The two plugs should be mirror images.
  • Check the part number on the adapter and make sure it is the same as the listed fit for your vehicle.
  • If all connections are correct, proceed to Method 2.
Verifying Correct Wire Connections for Plug-In Installs Image

Method 2: Testing for the Brake Signal

  • Use a 12V probe-style circuit tester to verify that power is present on the blue wire behind the brake controller when you use the manual control (Figure 2). If no power is present, the brake controller may be malfunctioning and require replacement. See video for reference.
  • Without the trailer plugged in, use a circuit tester to verify that power is present at the vehicle 7-Way when the brake pedal is pressed or the manual control is used. The electric brake pin should be in the 5 o'clock position. If no power is present, proceed to Method 3.
  • With the trailer connected, check for power on the electric brake wire coming out of the trailer's 7-Way plug. You can repeat the test on this wire, moving further back toward the magnets each time. If power stops, look for a short or ground issue (Method 3).
Testing for Brake Signal Image

Method 3: Looking for a Short or Ground Issue

  • If controller was hard wired (controller wires were spliced - no plug used to connect to OEM brake controller wiring), verify that the white ground wire is attached to the negative battery terminal on the vehicle.
  • Check along any wiring that was run from front to back on the vehicle and look for spots that have been nicked, pinched, or rubbed and have copper wire showing through the jacketing. Wrap any damaged areas with electrical tape.
  • Inspect the trailer wiring that runs from the trailer plug, again looking for any damaged spots (Figure 3). Wrap any damaged areas with electrical tape or replace the wire section, if the damage is great enough.
  • Look inside the front and back sides of the vehicle and trailer plugs to determine if any white or green corrosion has accumulated over time. If you see any corrosion, you will need to either thoroughly clean the plug or replace it. A wire brush works best for cleaning.
  • Check the wires on the trailer brake magnets. Each magnet should have two wires: one for power, and one for ground. Make sure that the ground wire is attached to a clean metal area without any paint or corrosion. The power wire should be intact and have a solid connection to the electric brake signal wire. It does not matter which wire does what, just that one wire is powered and the other is grounded.
Looking for a Short of Ground Issue Image

Method 4: Inspecting the Brake Assemblies

Inspecting the Brake Assemblies Image

For more information, see:

Updated By: Dani S.Last Updated: 3/4/2021

Questions and Comments about this Article

K C.

My trailer break controller does not disengage when I initially stop pressing the break pedal. If I tap the pedal after initially releasing the break pedal it disengages?

Etrailer Expert
Reply from David B.

Sounds like an issue with your stop light switch. Check out the link below it will help you troubleshoot the issue at hand. If you have any other questions let me know, I'll try to let the sunshine on the issue.

Verlyn H.

I have had a tekonsha P3 that I have used without problems for at least 4 years or more. Starting last week it no longer works. It shows the trailer connected and it show battery voltage and stop voltage when I push the brake but has zero output voltage and Amps. If I flip the switch on the controller it shows output voltage but no Amps and it does not stop the trailer. What would cause controller to not have any output?

Etrailer Expert
Reply from Les D.

@VerlynH disconnect the P3 from your truck, then measure voltage at the black wire coming from the truck. This should measure 12 volts. If not trace the wire back to its fuse, and then to battery source. If that works, then reconnect the harness to the P3 and (with brake depressed) measure voltage at blue wire. The voltage should go up as the brake pedal is depressed further. Let me know what you find.

Reply from Verlyn H.

@LesD

Reply from Verlyn H.

@LesD -- The black wire shows 12.2 volts - steady. The Blue wire - when connected to the P3 is intermittent and variable. sometimes it won't show any voltage with or without brake being depressed. Sometimes it flashes a quick voltage and goes off again. sometimes it will show 9-11 volts for a a second or two. However, If I flip the manual override switch on the bottom the voltage stays steady at 6 volts - but doing the manual does not cause the trailer to brake. I also checked with another trailer and though it shows the trailers connected - it will not show any output when braking.

Chris

Just hooked up P3 to 2007 Ram 1500. No power up. It’s wired to factory harness with quick connect. I did notice that the 3rd Brake bulb is possibly blown as I hit the brakes and no light, but the cargo light works. Would that affect it?

Etrailer Expert
Reply from Les D.

@Chris your wiring adapter has four wires on it. Black - 12V from Battery Blue - Brake voltage running to connector on back of truck. Red - Brake pedal switch White - Chassis ground Let's check where the black wire connects to the truck quick connect port. If your truck did not come with a tow package, the fuse may be omitted. Also ensure that white chassis ground is connected.

Reply from Chris

@LesD That is the connector that I have. The truck has towing package equipped. I looked at all of the wires leading up to the connection and it look right. I replaced the bulb and the 20v fuse for third break light.

Etrailer Expert
Reply from Les D.

@Chris when you completely remove the harness that runs from the truck to the controller, and then (on the truck) look where the black wire connects to the truck, what is the voltage there? Also, are you saying that the third brake light does not work when the P3 is connected, or the third brake light does not work at all?

Ronny B.

Installing a electric break up to a 2021 Freightliner it's getting all the signals but it won't put a signal out except my hand will not put a signal out when I press the brake

Etrailer Expert
Reply from Les D.

@RonnyB I would like to help. What kind/model Freightlinner do you have. What brand and model of brake controller do you have?

Gary S.

1996 suburban 2500 with the Tekonsho voyager controller. My question is my slide bar manual braking is not working. The pedal brake works fine. I have owned this controller for about 3 yr. Any help would be greatly appreciated.

Etrailer Expert
Reply from Les D.

@GaryS Is your Voyager displaying a green light that all is ok, and trailer is connected? When you squeeze the slide bar does indicator go red or go off? Disconnect the trailer and measure the voltage on the vehicle side on the blue brake wire in the 5 o'clock position on your 7 way connector. As the brake peal is depressed, or the manual side activated, the voltage should go up to around 12 volts. Could be a bad brake wire on the vehicle side or the trailer side. Let me know what you find out.

Reply from Gary S.

@LesD Thank you very much for your quick response. I can't connect to my trailer right now. But i did check the voltage at the pin and got 9 volts. The trailer brakes worked fine with the foot brake just not the slide. I did get a green light when connected to trailer not sure about it turning red while braking. Thanks again for your help any further suggestions would be greatly appreciated. Have a safe and happy New Year.

John S.

We just bought a brand new camper. Towing it with a 2013 Yukon. We were about a mile from the RV dealer when the Prodigy p2 controller started showing oL and I would lose brakes. Sometimes it would show sh when stopped. Everything works perfectly when stopped. I hear the brakes engage and see no issues. At a slow speed it sometimes works fine. But as soon as I am moving more than a couple MPH, I get oL and no brakes. Occasionally, it might get up to .8 power for just a second before it drops to oL. I want to believe the problem is with my 8 year old truck and not my right off the line trailer, but I am at a loss. I bought a new controller (also a P2) which strangely worked fine for a test drive around town with the trailer, but now does the exact same thing as the other controller. I installed a new connector on the back of the truck and re-hardwired the controller under the dash and even ran a new brake wire from the controller to the truck connector. No change. The maddening thing is I cannot replicate the problem when stopped. The plug-in tester shows things are fine. I hook up to the RV and hear all the brakes engage. I even jacked up each wheel and spun them by hand and the brakes all engaged fine. It is only when I am hooked up and moving that I have the issue. The only thing that I am not sure might be a clue is the brake light on the plug-in tester flashes every 10 seconds or so. More like a flicker. Don't know if that is normal. I've seen the stuff online about problems with the wire running through the axle (which it does) and worn magnets, but this trailer was literally built on 8/19 and has only the miles it took to drive it from IN to NC. Before I take the trailer back to the dealer, is there anything else I should/can do to rule out the truck? Thanks.

Etrailer Expert
Reply from Victoria B.

The fact that the controller would sometimes throw the "SH" code when you were stopped lines up with my first thought after reading your situation. It sounds like you have a brake signal wire that is shorting, likely to the frame or the axle, as you are traveling down this road, which then causes the brake controller to detect an oL - overload. This could be a pinched wire or one that got damaged in a freak situation even though your trailer is new. I understand wanting it to be an easier to fix issue on your truck, but I think the trailer's wires need to be looked over for any damaged or melted wire insulation.

Reply from John S.

@VictoriaB Thank you for the feedback. I rigged up a test light to put some load on the brake pin of the connector on the truck. This allows the controller to show connected and I could drive around and try to duplicate the problem without the trailer attached. As expected (feared) I was not able to duplicate. Without the trailer, all the test braking worked fine. high speed. low speed. Hard stop. All the conditions that would normally result in the oL condition worked just fine without the trailer. I did still get the SH, but I am confident that was just because I was using a light as my test which was an always closed connection so the controller was seeing it as a short. I am now convinced that the problem is on the trailer. I will be taking it to the dealer to hopefully get it resolved quickly. Thanks for the help.

Jacob

I got a after market brake controller installed in my truck, it’s been working fine up till now but yesterday I noticed that my dexter trailer brake actuator never shut off. It’s keeps running continuously. Brakes just have a very slight drag to them. It’s an hydraulic brake system. Do you have any suggestions what it might be? Thanks

Etrailer Expert
Reply from Victoria B.

I have two thoughts on what might be happening that you can check out. One, there may be a voltage leak on your brake signal wire causing the voltage to be higher at the trailer connector than it is coming out of the back of the brake controller. You could use a voltmeter to see if this is happening. The other thing to check is your trailer's breakaway switch. If the breakaway switch is pulled, even slightly, or is damaged, that could send brake power to the actuator and causing the drag you're noticing.

Richard D.

Everything was working just fine until one day I noticed that the brakes were not actually activating on my trailer. The controller indicated that everything was working fine. So I tried the manual lever on the controller and it appeared to be working, but the brakes were not applied. I don’t hear the magnet click when I use the manual lever or when I use the brake pedal. However,The numbers roll pass on the brake controller so it’s acting like it’s working. I checked all the fuses and the cabling. Everything looks fine. I’m thinking it’s the controller that is the problem. Any thoughts?

Etrailer Expert
Reply from Victoria B.

There are a couple of tests you can do to help narrow down the source of the issue. You will want to test the voltage on the brake wire at a couple of different points along the line, which will tell you where the loss of power is happening. I have linked a tech bulletin that has more details on this process.

Reply from Richard D.

@VictoriaB thank you so much. It was one of the IDC electrical connectors. A ground wire had pulled loose. I took it apart, re-inserted the wires and clamped it down again. Easy fix! Thank you.

Nellie

What does it mean when the read out on my brake controller just shows an r?

Nige

My brakes are wired to rear tail light but when I put my foot on the brake, the electric brakes work sometimes not all the time. Basically if I brake and they aren’t on, I wiggle the pedal and they turn on. How does wiggling my brake pedal side to side affect the on off status of the electric brakes? What needs replacing or fixing? Brake lights always work when I press brake. Have a holden Colorado 2013 and Hayman Reese electric brakes.

Etrailer Expert
Reply from Jon G.

It sounds like you have a loose wire connection or a bad ground somewhere. The brake light circuit and the actual brake circuits are 2 different things which is why your lights are working just fine. I would start off by checking the connections on your brake controller and then moving on from there. You might want to check around the brake pedal too to see if it is touching wires and maybe rubbing against them and causing them to become loose when you press the pedal down.

Reply from Nige

@JonG checked all wiring and can’t find any issues. Can’t replicate the wiggle brake on off anymore. It’s working up to about 4 seconds after car starts now. Then stops and doesn’t matter what gear it’s in it always stops after about 4 seconds after key start. Tried disconnecting redarc isolator.

Etrailer Expert
Reply from Jon G.

@Nige It could be that you have a bad brake controller but honestly if you aren't able to find anything wrong with the wiring then you'll want to take your setup to a shop and have them look at it for you. A wiring problem is really the only thing that we would know of that could cause that issue.

Reply from Duncan

@Nige Hey mate. Got identical problem with hayman reece brake controller not working 4 seconds after starting my colorado. What did you do to fix yours?

Reply from Nige

@Duncan changed the wiring for brakes to the trailer plug brake cable instead of tail light. Colorado have a funny voltage on brake lights. Also changed my power to run off cigarette plug instead of direct attach as my car battery was going flat when not in use - which has seemed to have problem that problem too.

Reply from Duncan

@Nige Cheers for your reply. I took the colorado and van for a spin to check ok without doing anything and about 10 mins into the run, controller started working properly and hasn't missed a beat since. Works sweat. I bit weird.

Scott D.

Hi, I have a 2012 Toyota Tundra. I have the C51362 plug to the truck side. I plugged in curt venturer 51110 controller to the harness. The green light flashes and truck brake lights come on as soon as I plug the controller in. The keys where not in the ignition. The 7 pin looks great, no signs of corrosion or damage. I am puzzled. I am unable to use the controller.

Etrailer Expert
Reply from Jon G.

Yeah that's not good. I would venture to say that the 12V power pin is somehow backfeeding into the controller and going to your stop light switch. The problem could be with your OEM wiring, the adapter, or even the controller. What I would do is test the pin that pairs with the pin for the red wire on your adapter to see if it's constantly hot or not. If it isn't then plug in the adapter and perform the same test. If all of that checks out then I can only assume that the controller is the issue and it probably needs to be replaced.

Reply from Scott D.

@JonG hi Jon, it was the brake controller, we bought 2 of the same brake controller, one for spare, just in case. Well both were bad out of the package. The third is working as it should. Thank you for your help

Etrailer Expert
Reply from Jon G.

@ScottD Oh my, that's crazy that you would have 2 bad ones like that. I'm glad you were able to get it figured out!

Korey G.

The brakes on the trailer work when jumped directly with a battery but not when hooked up to my truck. The plug in at the truck shows power and the light on my brake controller comes on when trailer is hooked up. I just re wired the brakes on the trailer from the tongue all the way back to all 4 brake assembly’s and I still have no brakes. Please help.

Etrailer Expert
Reply from Jon G.

Have you checked the wiring on your truck or tested the blue wire 6" from the brake controller? If your trailer brakes are working properly then that means you've isolated the issue to be on your truck ends of things.

Paul M.

When I start my truck my breaks are not working as they shouldn’t. The first time I engage the breaks with the controller or the pedal all four breaks engage fine. When I release the breaks three breaks disengage but one stays engaged. I can hear the magnet humming and the wheel will not move. Not sure where the power could be coming from?

Etrailer Expert
Reply from Jon G.

You should have a 12V power pin in your 6-Way or 7-Way connector. I would check to make sure there isn't any crossover there. This can happen through corrosion on the connector or maybe damaged wiring further down on the trailer.

Joe O.

So the other day i hooked up my trailer and realized that the trailer brakes (set to the same number as always) were doing almost nothing. Now when i turn the controler way up it does start to do something. Would this be a problem with the brake controler or in the wiring

Etrailer Expert
Reply from Jon G.

I honestly think you have a bad connection or ground somewhere. It's possible for brake controllers to go back but it's MUCH more likely that something is going on with the wiring. If you check all of your connections to make sure they are clean and secure and that all of your wiring is in good shape then you can look at the brake controller. Another easy way to test this is to cut the blue wire about back from the brake controller and see what the power looks like up close to the controller.

Chad K.

My brake control is showing 4.6VDC directly out of the control pigtail (same at the 7 pin) with no brakes applied and 12VDC with brakes applied. I've read i should have 0 voltage with no brakes applied. Could this be a faulty controller? I can't have it hooked up because it smokes the trailers brakes

Etrailer Expert
Reply from Jon G.

It could be a faulty controller or it could mean that you're getting constant power input on the red wire going into the controller. Check the red wire first and if that isn't hot then the controller would be faulty. If it is hot all the time then that means you're connected to the wrong wire and you need the find the cold side of the brake light switch that's only hot when you press the brake pedal.

Scott L.

Hi on the brake control. With a tester on the red and white wires. When I push on the brake pedal should I be reading 12 volts?because I am not. With trailer connected e brake works but doesn’t show that trailer is connected

Etrailer Expert
Reply from Jon G.

The red wire should be getting power whenever you apply your brake pedal. I would double check to make sure that you have your brake controller installed correctly. If your wiring isn't correct then that could be why you're getting the "trailer not connected" error.

Reply from Scott L.

@JonG Thank you John I’m sure it’s somewhere with the connection in my truck thanks for your help

Reply from Scott L.

@ScottL I have the controller installed in my truck. Had trailer package on truck. Has worked for years and we just tested it and still works. Not getting power from the brake pedal was wondering if there is a fuse on that circuit. 2004 Dodge ram 1500 with trailer package.

Etrailer Expert
Reply from Jon G.

@ScottL I checked out the online version of the owner's manual and it said that on the underside of the fuse panel box is where you can see what fuses are for what functions.

Neko

Just installed promise iq 90160. Shows trailer connected. When I press brake pedal, does not engage or register on brake assist. No lights on trailer or truck light up. When I press the manual override calibration slide, brakes engage and lights work? Why won’t the pedal when pressed, engage trailer brakes or trigger brake lights but the slide when pressed does?

Etrailer Expert
Reply from Jon G.

I don't know why your trailer taillights won't work but I can say that if you're sitting still when you use your brake pedal the reason that it isn't applying the brakes is because it's a proportional controller. Meaning it has a sensor inside that can tell you aren't moving and don't need to actually apply brakes to the trailer.

Randy L.

Just installed and Curt 51140 Triflex with pigtail and when I connected my 2019 Chevy Silverado to my 2019 travel trailer the one decimal didn't change to 2 decimal points as I read it should. I haven't towed the trailer to check to see if the brakes are working. Any ideas on the 1 decimal reading? Thanks.

Etrailer Expert
Reply from Jon G.

If you only have 1 dot then that means it isn't detecting that your trailer is connected. You might need to turn your truck on (if you haven't already) and make sure your truck and trailer connectors are clean and free of debris.

Rob S.

I Just purchased a travel trailer, and the brakes seem to lock up for a second when slowing down, regardless of what the gain is set at. Only if it is at zero to i not get the jerk braking. also the display screen shows no output for braking and when i use the manual lever it says no trailer is connected.. any suggestions?

Etrailer Expert
Reply from Jon G.

I would inspect your entire setup to be honest. If your brake controller isn't reading a trailer connected but your brakes are locking up at times then you could have your connector pinned incorrectly and/or some corroded wiring that is crossing signals. Check that all of your wiring is secure and clean and that your trailer brakes are adjusted so that there is a slight drag when you are freely spinning the wheel.

Geoff R.

2016 Ford F150 Lariat (3.5 litre Eco Boost) towing a 2015 24 foot Cougar travel trailer that I've been towing with this truck for 5 years without issue: On a recent fishing/camping trip, I had been driving for around 5 hours and as I neared my destination, I decided to stop and fill my gas tank on the way there, rather than on the return trip. After filling up, I jumped in the truck, started it up and went to pull away from the pumps, but I was unable to move. I also got a message on my dashboard display saying "Trailer Wiring Fault". Thinking that perhaps my trailer had somehow become unplugged from the truck, I got out to take a look. Everything looked okay (including the break-away switch), so I unplugged the trailer to have a closer look at the plug and receptacle and I heard the trailer brakes release and the truck (running, but in park) settled forward slightly. I plugged the cord back into the receptacle and I could hear the trailer brakes engage again. Just to be sure, I tried again to move the vehicle, but the brakes were definitely engaged. So, I cleaned up the connections, checked fuses, pulled the pin on the break-away switch and plugged it back again, but the brakes remained engaged. Exasperated, but being very close to my destination, and only having to drive on a quiet country road, I decided to just unplug the trailer and drive to my camping spot. Throughout the week (before and after fishing) I attempted to sort the problem out. I visually inspected all the wiring on the trailer for the trailer brakes and checked all the connections, but everything looked good on the trailer end of things. On the truck though, I was still getting a "Trailer Wiring Fault" alarm on my dashboard display as soon as I put the truck into drive and started moving. I finally decided to take a day off fishing and went to a nearby Ford dealership and talked with them about the problem, describing everything that I had done to troubleshoot. They said that it could be a number of different things that are causing the problem, but recommended that I start by changing the 7 pin receptacle on the truck. So I bought a new 7 pin receptacle, installed it on the truck and nothing changed. Fast forward to today: I'm back home and I've had the truck into the dealership where I bought it and they've checked it over and say they can find nothing wrong. They're now asking me to bring my trailer in with the truck, but because I couldn't safely bring the trailer home from my trip, I decided to leave it at a nearby storage facility and drove home without it. Anyone out there have any other ideas about the source of this problem. Personally, I think it's the integrated trailer brake controller that has malfunctioned. I'm told that it's a $250 part - wondering if I should just have it replaced?

Etrailer Expert
Reply from Jon G.

It could be the OEM brake controller or a bad ground really. Do you have the ability to hook up to a different trailer to see if your truck still acts that way? If it does then you for sure know the issue is on your truck.

Norm

we have a 2021 chevy 3500. when i hook up our 5th wheel and test the brakes before leaving the driveway. they work fine. about 1/2 mile down the road . the brake controller shows no display and the brakes don't work. display on dash says connection good no faults. any ideas.

Etrailer Expert
Reply from Jon G.

Is this an OEM brake controller? Typically when there are issues like this it's the result of a bad ground or a damaged wire/connection somewhere. This could be either on the tow vehicle or the trailer.

Dave D.

I've been troubleshooting a pulsing brake problem, my dual axle trailer has a distinct pulsing when braking around 50% or more and the frequency is not the same as the wheel rotation. Wiring is factory (12-14 gauge wiring) but there are some connections I can't get to to check, I've checked and the trailer draws a little over 12 amps while stationary at max gain and the resistance of each magnet is normal around 3 ohms. I tried brake isolation and found the pulse never really goes away, but increases as I hook more wheels up. I suspect this to be an amperage issue due to a faulty connection but wanted to get opinions on the matter. My ultimate plan is to rewire them all with 12 ga wire and eliminate the thru-axles wires. Thoughts? Thanks!

Etrailer Expert
Reply from Jon G.

That's a really good plan. The vast majority of the time when there are inconsistencies like that it's because of faulty wiring.

Steve M.

When manually pressing the brake controller switch I get full power to trailer brakes depending on how hard I press, but when using the foot pedal my controller is only showing 0 or 5, meaning I’m using mainly the truck brakes to stop the trailer. Any suggestions?

Etrailer Expert
Reply from Jon G.

Do you have your controller set to max settings, and is it a time-delayed controller or a proportional controller? If you don't have it set to max then that would explain why it isn't showing full power with your foot pedal, and then if it's proportional then you won't see much power unless your towing rig is actually moving due to the internal sensor in the controller.

Ryan

What if you have a functional brake controller that you’ve tested , and works, on other trailers, just installed new brake assemblies on both sides, adjust both assemblies properly, and can hear the brakes electronically activate when the brake pedal/manual override is being pressed, and yet there is still no braking happening on the trailer? Oh, and the brake controller settings have been set all the way up and down, and everything in between, still no change. Thoughts?

Etrailer Expert
Reply from Jon G.

To me that either sounds like you need to recheck the adjustment of the brakes (you should have a slight drag when free-spinning the tire) or you have a short somewhere that is reducing the power being sent back from your brake controller. Since the brake controller has been tested and works with other trailers the issue is definitely on the trailer side of things.

Ryan W.

What if you have power to the red stop wire when the brake pedal is not pressed and my Redarc Tow-pro elite is giving me an error of there being a short in the trailer brake wiring? It’s a new travel trailer and I have 13V all the way back until I get to the plug in 7 pin harness. Before the black box is 13v and after the box at the 7 pin female adapter is reading 6v. All camper lights work, but the error for a short in the blue wire.

Etrailer Expert
Reply from Kef G.

Have you traced all of your wires? Look for any corrosion or pinch points. If you find any, replace those wires.

Reply from Ryan W.

@KefG I didn’t see anything out of the ordinary but will pull the plug and play wires and check.

Etrailer Expert
Reply from Jon G.

@RyanW While you're checking your wires it would be a good idea to double check the connection with the red wire on your brake controller as well. This should be connected to a wire that only gets hot when the brake pedal is pressed. If the wire it's connected to right now is always hot then you'll want to connect it to a different wire.

Reply from Ryan W.

@JonG thanks for all the replies. Found a pinched wire on the emergency brake on the travel trailer.

Etrailer Expert
Reply from Jon G.

@RyanW Glad to hear it!



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